"It tummeled oot."

Opportunity for a double update.  ;¬)
It became obvious that my suspicion was correct:-
Somehow the wee spud had both rooted and become detached from the wee taty, which I had previously removed.
Also that the orchid has finally decied to shove out a new root or three. All the fine hairy stuff appears to belong to the spud since, apart from being attached to the plant, it bears ZERO resemblance to a Phalaenopsis root.
Result:-
I was able to easily remove the interloper.
I had no excuse for not potting up the orchid.